Matching backplates to HDRIs

aaráribel caađo

I recently bought an HDRI with matching backplates. The backplates have information about the settings/lens used on the camera (e.g., "28 mm-1-500 sec at f - 9,0"). Is there anyway to match this with Iray?

mjc1016

28mm is a pretty wide angle lens...why would you want to render with that wide an angle lens?

 

aaráribel caađo

To match the settings used on the original photograph in the backplate. If it's not matched, the perspective on the 3D elements will be off. Ideally, we could plug in camera and lens information which would match the lens distortion as well, but that's probably way too complicated for most users and overkill for 99.99% of DAZ uses.

Fishtales

Set a camera up with the lens settings e.g. 28mm and set the rest in Tone Mapping e.g. speed 500. f/stop 9. You will probably need the focal length too set in the camera settings if you want DOF in the image.

aaráribel caađo

Thanks. I set my camera to 28mm for the render I did yesterday, but didn't think aobut the other film settigs. It worked okay visually matching the exr output, but nexttime I'll try it with tone mapping. I've never done more than adjust speed, so playing with both speed and f/stop will be a nice bit of learning.

mjc1016

My point is, they are going to be 'off' anyway...you won't get 'scale' right.  Without knowing the distance between the camera and an element of the backplate you can't scale the dome to actually fit...so the models won't be scaled correctly so all the fiddling with matching focal lengths won't matter.

aaráribel caađo

The matching part was a huge pain when I worked with this. I set my camera to match the specs, but I had to do a whole bunch of renders to get the HDRI to get close to the backplate. However, with all the infromation now caputures by cameras, you should be able to match things up pretty well with the camera data, at least if the camera is set on the same tripod that was used for capturing the HDRI—that would give the same 0-point corrdinates, so all you'd need was lens and rotation data. At least I think that's correct. You might need reference geometry to position via height data.

mjc1016

aaráribel caađo said:

You might need reference geometry to position via height data.

At least...and for anything short of rendering in very large sizes, the amount of work setting it up is probably going to out weigh any advantage.  In other words, it's not likely to be noticeable.